The role of falx cerebri in the selective vulnerability of the splenium in the corpus callosum

The corpus callosum, the largest white matter tract connecting the cerebral hemispheres, is anatomically divided into the genu, midbody, and splenium. Among these subregions, the splenium is particularly vulnerable to traumatic injury, with the underlying biomechanics largely unknown. We hypothesized that the falx cerebri contributes to splenial vulnerability because of its anatomical proximity to the posterior corpus callosum and its substantially greater stiffness relative to brain tissue. To test this hypothesis, a high-resolution finite element head model with explicit representations of the corpus callosum subregions was used to simulate ten head impacts with and without an anatomically and mechanically detailed falx. Peak strain, strain rate, and shear stress were quantified and compared using linear mixed-effects models. The results showed the inclusion of the falx consistently increased strain, strain rate, and shear stress in the splenium relative to the genu and midbody, whereas this preferential splenial response was not consistently observed without the falx. Statistical analyses confirmed significant region-dependent effects, with falx-induced increases significantly greater in the splenium than in the other subregions (p < 0.05). These findings verified that the falx selectively amplifies mechanical loading within the splenium, providing a biomechanical explanation for its frequent involvement in neurotrauma patients.